This section provides background information related to the present disclosure which is not necessarily prior art.
Injection molded components are widely used in the automotive industry for various trim pieces and other parts that are installed both inside and outside a vehicle. Such injection molded components are typically made of a thermoplastic material. Typically, injection molded components are lighter and cheaper to make in comparison to metal parts, particularly when the part requires complex shapes and curves. Injection molded components also tend to be more corrosion resistant than metal parts, which are prone to rust. However, consumers typically associate injection molded components with inferior quality largely due to their weight and appearance. Accordingly, there has been a trend within the automotive industry in recent years to improve the quality of injection molded components, including making improvements to the appearance of these components. This is especially true within luxury brands and vehicles with upgraded trim packages. These advances have led to the proliferation of injection molded components that simulate (i.e. have the appearance of) metal parts.
One area where improvements in injection molded components are notable is in vehicle door handles on both the inside and outside of the vehicle. At one time, vehicle door handles were commonly made of metal. Due to cost reduction efforts, most vehicle door handles are now made of plastic using injection molding processes. While this change gives automakers more options regarding the shape of the door handle, standard injection molded components have a dull surface finish and are often perceived by consumers as having a “cheap” appearance. One way that automakers have “dressed-up” the appearance of these injection molded components is by chrome plating vehicle door handles. Examples of chrome-plated vehicle door handles are found in U.S. Pat. No. 7,544,319 entitled “Vehicle Handle Assembly With Antenna,” which issued to March et al. on Jun. 9, 2009 and Canadian Patent Application No. 2,047,625 entitled “Injection Molding Process For Platable Plastic Substrates,” which was published on Jan. 25, 1992 naming Robert L. Coombes, Jr. as the inventor. Both of these references teach vehicle door handles that are manufactured using a conventional two-shot injection molding process. The vehicle door handles have two plastic layers, an inner layer that is formed by the first shot and an outer layer that is formed by the second shot. Both references explicitly call for the outer layer to be made of a platable plastic material. In other words, the plastic material forming the outer layer is selected from a group of plastics that are compatible with the chrome plating process (i.e. plastics that chrome can adhere to). Chrome plating is applied to the platable plastic material to create a vehicle door handle that ultimately includes three layers—two plastic layers and one layer of chrome plate. As explained in the references, the chrome plating can be applied by immersing at least part of the vehicle door handle in one or more electroplating baths, where metal is electrolytically deposited on the surface of the outer layer. This is a fairly lengthy and expensive manufacturing process because the vehicle door handle is not a finished component when it is removed from the mold. Also, the chemicals used in the chrome plating process are hazardous to the environment and can create adverse health effects when exposed to humans. Therefore, caution must be used in the handling and disposal of these chemicals.
Although the chrome plated vehicle door handles produced by this process have a metallic appearance and are thus more aesthetically pleasing than un-plated injection molded door handles, they suffer from a number of problems in addition to the time, expense, and environmental drawbacks that are associated with the chrome plating process. First, the metal that is deposited on the outer layer of the vehicle door handle is susceptible to corrosion. As such, the chrome plating itself may rust even if the plastic material forming the inner and outer layers cannot. Second, the chrome plating can bubble, peel, and chip. This not only detracts from the appearance of the vehicle door handle, but the exposed edges of the chrome plating tend to be sharp and can cut a person's hand when they grab the vehicle door handle during ingress or egress. What is needed is an alternative solution to chrome plating that produces a plastic vehicle door handle with a metallic surface finish at a reasonable cost.